OBJECTIVES: 1) Unconjugated plasma estriol (E3) will be measured up to six times in 2,000 pregnant patients between 30 and 38 weeks gestation. The patients will be divided at random into a study and a control group of equal size. Study group patients will be referred for antepartum fetal heart rate testing (AFHRT) and additional studies if plasma E3 levels or patterns are abnormal. Plasma E3 results of control group patients will be blinded. It is the objective of this study to determine whether screening of apparently uncomplicated pregnancies reveals unsuspected problems and thus reduces perinatal morbidity and mortality. 2) Patients with pregnancies complicated by preeclampsia and/or intrauterine growth retardation (IUGR) will be managed with AFHRT, ultrasonic studies and amniotic fluid L/S ratio determinations. Plasma E3 will be measured but the results will not be made available for the clinical management of these patients. It is the objective of this study to assess whether plasma E3 may be utilized for clinical management of these patients (criteria for delivery, incidence of falsely abnormal and falsely normal results). 3) Patients with prolonged and accurately dated pregnancies will be randomly divided into 2 groups. All patients will have twice weekly plasma E3 assay and weekly AFHRT. Group 1 patients will be delivered if AFHRT results are abnormal while E3 results remain blinded, and group 2 patients will be delivered for abnormal E3 and/or abnormal AFHRT results. The objective of this study is to assess the value of plasma E3 assays in managing prolonged gestation. 4) Patients with presumably prolonged gestation and poor dates will be followed with twice weekly plasma E3 assays and weekly AFHRT. Only if both tests are abnormal a patient will be delivered. It is the objective of this study to assess the value of serial plasma E3 assays in term or post-term gravidas with poor dates. 5) Renal clearance of estriol-16-gamma-glucuronide will be determined in normal gravidas and in patients with severe preeclampsia or class D, F and R diabetes in an effort to assess whether this is a good test for renal function.